måndag 17 september 2012

Incorrect Flight Theory at the Smithsonian

Using this poster, students can explore the fundamental physics of flight.

Students will be able to describe how Bernoulli’s principle enables airplanes to fly.

Wings are designed so the air moving over the top of the wing is forced to speed up more than the air moving below the wing.

A common explanation of lift states that air moves faster over a wing’s curved upper surface because it has farther to travel than air moving under the flatter lower surface. This explanation is wrong!

How can an airplane fly upside down? Wing tilt is the trick. Tilting the upside-down wing upward forces the air traveling over the wing to speed up more than the air passing beneath the wing. The difference in air pressure results in lift.

Activities on the following pages (4-6) enable students to discover for themselves how moving air creates changes in air pressure and how Bernoulli’s principle is put to use in wing design. The results are often surprising!

OK, so young students are taught that lift comes from lower pressure above, which does not come from longer distance above (wrong explanation!), but somehow from tilting at least for an upside-down wing.

But this is confusing nonsense which does not explain anything. To say that lift comes from lower pressure above is a trivial tautology. To say that tilting forces the air to travel faster above without telling why and how, gives no information, only further mystery.

The fact that the National Air and Space Museum feeds to minds of interested students with nonsensical disinformation is one of many indications that present aerodynamics education has collapsed. Who is responsible? AIAA?